Apparatus for cleaning tanks



July 20, 1943. J. VA N "seminar: 2,324,304

AFPARA'PUS FOR QLEANING TANKS Filid July 11, 1942 2 ShIItI-Shfl'. 1

0.15 1.9 INVENTOR.

M ATTORNEY;

J y J. VAN G'ELDEREN 2,324,804

APPARATUS FOR CLEANING TANKS Filed July 11, 1942 2 SheetsSheet 2 ,60 .52, 140 u L I ll HIHHIHH mmu ATTORNSY.

Patented July 20, 1943 UNITED STATES PATENT OFFICE Application July 11, 1942, Serial No. 450,564 8 Claims. (C1. 141-1) This invention relates to apparatus for cleaning tanks such as oil tanks, and is herein illustrated in some detail as embodied for the cleaning of oil cargo tanks on sea-going vessels.

Such tanks may carry any of several kinds of .oil, such as fish oil, tung oil, petroleumproducts varying from the heavy lubricating oil used for cylinder oil to gasoline, linseed oil, andmany others, such as tar, asphalt and crude oil.

At the end of a voyage it is usually necessary to clean the tanks after emptying them, for almost always a deposit clings to the metal of the tank which will contaminate another oil put into the tank and will soil the packings or'body of other cargo packed into the tank. I V

To remove these contaminating coatings it has been customary to scrape the interior of the tanks by hand, employing unskilled labor, although sometimes the tanks have been steamed out by high pressure steam, say upwards of seventy-five pounds pressure, and both scraping and steaming often have been found needful.

For removing many oils the steaming out is very unsatisfactory, and attempts have been made to make a more eflicient process by heat ing some volatile solvent for the oil or gum which coats the walls of the tank. The best solvents for this purpose, in many cases, would seem to be the very hot ethylene chlorides, but these are objectionable for many causes. For example they hydrolyze and form corrosive free hydroe chloride acid in the presence of steam formed by water present and this acid rapidly attacks the iron of the tanks.

Moreover, the tanks expand under the heat of high pressure steam, and are'ser'iously strained thereby. often even expanding enough to shear 'off the heads of rivets which, hold parts that expand to a less extent. Such strains, resulting in sheared rivets and sprung seams, seem more ing it almost impossible for them to safely use volatile solvents, because of the danger .of'asphyxiation or of actual poisoning by the vapor given off.

According to the present inventionthe foregoing difficulties and objections are overcome and a relatively simple device is provided for cleanouter ing oil tanks, easily operable, and expensive to build.

In the form herein illustrated the wall of the tank is cleaned by steam, which may be low pressure steam, carrying a suitable chemical or solvent, kept in the stream by delivering the steam under low pressure yet enough to give it substantial velocity as it impinges on the tank wall.

In the form illustrated, a solution of' a suitable chemical is delivered into the flowing current of steam, and the steam flowing through a hose is delivered through a coverlying against the/tank wall but spaced from it by closed in sides. This cover limits heating, at any one time; to a small area; -The entering steam flows the device is inon, impinging with: its entrained chemical or solvent upon the wall ofthe tank, heats it and loosens thesgum, scale and-oil. The steam refiected away from the tank wall is illustrated as passing off through abase having an opening through the cover and delivering the steam and vapors. to the air outside the tank. a

According to the present invention the channel beams or other ribs of the vessel may be utilizedto hold. the cover in place and serve as guides for it, thus enablingthe pressure of the steam to. be utilized. in part as an impinging stream without imposing a heavy burden upon the workmen in holding the cover in place.

Other features and advantages will hereinafter appear.

In the accompanying. drawings:

Figure 1 is a sectional side view, largely diagrammatic, showing one form. of the invention employed in cleaning a cargo oil tank of a vessel.

Figure 2 is a section on the line 2-2 of Figure 1.

t Figure 2d diagrammatically shows the same parts when removing or applying the cover.

Figure 3is a section onthe line 3-3 of Figure 1.

Figure l is a face view of the cover in use on a larger scale, and with some parts broken away. Figure 5 is a sectional view on the'line 5- -5 of Figure 4.

Figure 6'is an enlarged detail showing one form of rubber flap.

Figure '7 is a sectional View on the line 'i--'l of Figure 4.

The invention is illustrated in Figure 1 as employed in cleaning-the inside wall plates ill of a tank in a Vessel shown as including hull plates bars or ribs l3, as well as top stringers |4, all beneath the deck I 5.

Access to the tank formed by the plates I is had through a hatch or manhole l6.

To clean the interior of the tank the workman descends into the tank through the hatch l6 carrying with him a cover device He fits the cover device I! over to one of the channel bars l3 by setting a recess |8, shown at the right hand side of the cover, opposite the projecting lip I9 on the far side of one channel bar l3, for this purpose the cover top being divided lengthwise along a line 20, and also sets opposite the projecting lip 2| of the other adjacent channel iron I 3 a recess 22 in the left hand side of the cover device top. This brings a fixed end 32 on the left hand section 3| of the cover device adjacent the plat l0, and the slidable end 28 of the right hand section 21 of the cover device adjacent the plate Ill. The two sides of the top "3' are then pushed until their recesses I8 and 22 fit over the lips |9 and 2| of the channel beams, and the slidable ends 28 and 29 pushed against th right hand channel bar |3. Then the empty space between the tongue 23 on section 21 and the rabbet on section 3| is filled with strips 25, 26, tongued and rabbetted to match. Other details will be more fully explained later.

When the workman has fitted both the sections 21 and 3| in place with their end pieces, he turns on the cleaning steam through a valve 34, so that the steam flows through a flexible hose into a metal half-inch discharge opening 36 near the center of the section 3| and allows the steam to impinge upon the facing plate H].

The steam he admits preferably carries cleaning or detergent or solvent materials or all three which are shown as introduced into a two inch steam line 37 to which the one inch hose 35 is attached. The chemical or other material is shown as introduced into the line 31 through one branch of a Y 38 into which it is forced by a piston pump or suitable injector which draws the material from a mixing and dissolving tank 40.

When the workman turned the valve 34 the impinging steam under the cover device I! cleaned the plate I!) and the unused and waste steam passed off through a two-inch discharge opening 4| near top of the section 3|, and was carried off through a canvas hose 42 to the outer air through the hatch It.

In order to carry off condensed water, dirt, oil, and particles of scale there is provided near the bottom of the section 3| a discharge opening 43, and the waste material flowing into the opening 43 is shown as continuously removed by suction.

For this purpose it has been found sufiicient to connect the discharge opening 43 by a hose or pipe 44 to the upper discharge opening 4| in its nipple 45 so that the suction of the outflowing waste steam continually carries off the waste in the opening 43 and through the pipe 42, delivers it outside the vessel.

In order to hold the temperature within the cover device I! at the best working point there is shown a pointer-type thermometer 46 which may be mounted in the section 21, preferably rather remote from the steam opening 36, so that the entering steam does not directly affect the thermometer 46.

The temperature may be regulated by a valve 48 in the opening 4|, shown as a butterfly valve with a hande 49 and a friction spring 50. Partly closing the valve holds a pressure of steam in the cover device, raising the temperature.

It has been found that a solution of trisodium phosphate of soda fed in at the Y 38, and showing a temperature of F. on the thermometer at 46, will satisfactorily remove some lubricating oils from an oil cargo tank. More rapid results were obtained when some pine oil was added with the tri-sodium phosphate.

Sodium meta-silicate was also found useful. A higher temperature, say F., was needed with other oils. Stronger alkalis could be used, and for special purposes sodium bichromate was useful.

Where speed was essential it may be advisable to use the surface action materials known as wetting agents either alone or in combination.

For obtaining the most rapid and cheap results preliminary tests must be made to determine the amount and kind of chemical agent best adapted for any given set of conditions, varying with the kind of oil, age of the coating, and temperatures.

There may also be provided a valved opening 47 near the bottom of the cover device for blowing in air if needful to carry off gases.

Under the conditions of working it is found that the steam is properly applied, and controlled, if confined by soft rubber curtains 5| extending from the edges of the ends 28, 29, 32, 33, which face the plate l0, so that the free three-quarter inch of curtain bends where it lies against the plate Ill. The curtains 5| have been found satisfactory when about inch thick and held to the respective ends by metal strips 52 along the inner edges of the curtains, see Figure 6. The curtains 5| are shown on the outer faces of the overlapping sliding ends 28, 32 and 29, 33 so that the strips 52 are on the opposite sides of the sliding ends and do not hit an oncoming end.

It is found that a substantial overlap of the curtains 5| sufficiently holds the steam. The

, curtains 5| also extend around the ends of the satisfactory there also.

The recesses i8 and 22 are shown as lined with soft rubber packing 53 to prevent undue escape of steam and cleaner. The packing 53 need not fit closely however, because the steam pressure is very low within the cover device I! as a result of the opening through the off bearing pipe 42,

and some escape of steam cleanses the flanges I9 and 2|, thus making it unnecessary to scrape them clean.

The top of the cover is provided with a pair of ears 54 carrying a bolt 55 on which swings a handle 53 to enable a man on the floor of the tank to manipulate it on the roof and upper walls where higher than his head.

In the form shown the recesses l8 and 22 in the cover device are preferably channelled out of solid wood timbers and the rest of the cover device built principally of wood to hold the heat. The wooden filler members 25 and 25 which are shown are respectively and 1 inch wide, thus accommodating the cover to all standard spaced channel bars, the cover I! being 25 inches wide and somewhat longer. A hook 58 may be pivoted on section 21, at each end, lying flat on its surface to engage any one of eyes 59 set to be engaged according to the spacers 25, 26, employed.

The slidable end 28 is shown lying above the cooperating fixed end 32, and is held against it by a guide 60, shown as nailed to the section 3| and extending over the major length of the slide 28. The slide 29 similarly slides in a guide 6| nailed along the edge of the section 3| and covering the major length of the slide 29.

It will be noted that the cover device ll fits channel bars projecting to the right. A reversely constructed device I! will be used on channel bars projectingto the left.

It has been found that three minutes steaming of any one point in a tank plate with the device of the present invention is adequate to clean it if the most effective chemicals are used. Thus straining of the whole tank at any time by heat is avoided because the heated spot is small and is seldom heated through.

Having thus described certain embodiments of the invention, what is claimed is:

1. The combination with a cover, of sides having flexible sheet rubber margins adapted to yieldingly bear against an oil-bearing surface, a connection through which steam carrying a chemical is delivered within the cover, a separate elf-bearing duct for the waste steam well above the lower edge of the cover, a second off-bearing duct near the lower edge of the cover, a suction pipe leading from the second duct to the first duct so that condensed steam carrying solids is sucked out of the second duct and carried off by the first duct connection.

2. The combination with a cover having flexible sheet rubber margins adapted to bear yieldingly against an oil-bearing surface, devices insertible to form part of the cover to vary its width, a connection through which steam carrying a chemical is delivered within the cover, a separate off-bearing duct for the waste steam well above the lower edge of the cover, a second ends adapted to bear against a fiat oil-bearing surface, sides adapted to fit n beams projecting above said surfaces, flexible margins on the sides and ends adapted to form yielding contacts with the oil-bearing surface, a connection through which steam carrying a chemical is delivered within the cover, a separate off-bearing duct for the waste steam well above the lower edg of the cover,

l. The combination with a cover, of projecting ends adapted to bear against a flat oil-bearing surface, sides adapted, to fit on beams projecting above said surface, flexible margins on the sides and ends adapted to form yielding contacts with the oil-bearing surface, a connection through which steam carrying a chemical is delivered within the cover, and a separate offbearing duct for the waste steam well above the lower edge of the cover, a second off-bearing duct near the lower edge of the cover, a suction pipe leading from the second duct to the first duct so that condensed steam carrying solids is sucked out of the second duct and carried off by the first duct connection.

5. The combination with a cover, of projecting ends and sides adapted to lie against oilbearing surfaces, flexible margins on the sides and ends which form yielding contacts with the surfaces, a connection supplying steam through the cover, an off-bearing duct for waste steam, and a pump for forcing a chemical agent into the connection, a second off-bearing duct near the lower edge of the cover, a suction pipe leading from the second duct to the first duct, so that condensed steam carrying solids is sucked out of the second duct and carried off by the first duct connection.

6. The combination with a cover, of projecting ends and sides adapted to lie against oilbearing surfaces, flexible margins on the sides and ends which form yielding contacts with the surfaces, a connection supplying steam through the cover, an off-bearing duct, for waste steam and a pump for forcing a chemical agent into the connection, and devices for altering the width of the cover.

7. The combination with a cover device of a connection for supplying steam thereto carrying oil-removing material, an off-bearing conduit, and devices whereby the cover device may be attached to channel bars of a metal tank to hold the device against the plates of the tank.

8. The combination with a cover device of a connection for supplying steam thereto carrying oil-removing material, an off-bearing conduit, and devices whereby the cover device may be attached to channel bars of a metal tank to hold the device against the plates of the tank, and flexible margins on the sides and ends of the cover device to form yielding contacts with the plate and channel bars.

JOHN VAN GELDEREN. 

